给定一个字典和一个字符数组，使用该数组中的字符打印所有可能的有效单词。
例子：
Input : Dict - {"go","bat","me","eat","goal",
"boy", "run"}
arr[] = {'e','o','b', 'a','m','g', 'l'}
Output : go, me, goal.
提问人：微软访谈
想法是使用Trie数据结构存储字典，然后使用给定数组的字符在Trie中搜索单词。
- 创建一个空的Trie并将给定字典的所有单词插入Trie。
- 之后，我们仅选择“ Arr []”中属于Trie根的子代的那些字符。
- 为了快速查找数组中是否存在字符，我们创建了字符数组的哈希。
以下是上述想法的实现
C++
// C++ program to print all valid words that
// are possible using character of array
#include
using namespace std;
// Converts key current character into index
// use only 'a' through 'z'
#define char_int(c) ((int)c - (int)'a')
//converts current integer into character
#define int_to_char(c) ((char)c + (char)'a')
// Alphabet size
#define SIZE (26)
// trie Node
struct TrieNode
{
TrieNode *Child[SIZE];
// isLeaf is true if the node represents
// end of a word
bool leaf;
};
// Returns new trie node (initialized to NULLs)
TrieNode *getNode()
{
TrieNode * newNode = new TrieNode;
newNode->leaf = false;
for (int i =0 ; i< SIZE ; i++)
newNode->Child[i] = NULL;
return newNode;
}
// If not present, inserts key into trie
// If the key is prefix of trie node, just
// marks leaf node
void insert(TrieNode *root, char *Key)
{
int n = strlen(Key);
TrieNode * pChild = root;
for (int i=0; iChild[index] == NULL)
pChild->Child[index] = getNode();
pChild = pChild->Child[index];
}
// make last node as leaf node
pChild->leaf = true;
}
// A recursive function to print all possible valid
// words present in array
void searchWord(TrieNode *root, bool Hash[], string str)
{
// if we found word in trie / dictionary
if (root->leaf == true)
cout << str << endl ;
// traverse all child's of current root
for (int K =0; K < SIZE; K++)
{
if (Hash[K] == true && root->Child[K] != NULL )
{
// add current character
char c = int_to_char(K);
// Recursively search reaming character of word
// in trie
searchWord(root->Child[K], Hash, str + c);
}
}
}
// Prints all words present in dictionary.
void PrintAllWords(char Arr[], TrieNode *root, int n)
{
// create a 'has' array that will store all present
// character in Arr[]
bool Hash[SIZE];
for (int i = 0 ; i < n; i++)
Hash[char_int(Arr[i])] = true;
// tempary node
TrieNode *pChild = root ;
// string to hold output words
string str = "";
// Traverse all matrix elements. There are only 26
// character possible in char array
for (int i = 0 ; i < SIZE ; i++)
{
// we start searching for word in dictionary
// if we found a character which is child
// of Trie root
if (Hash[i] == true && pChild->Child[i] )
{
str = str+(char)int_to_char(i);
searchWord(pChild->Child[i], Hash, str);
str = "";
}
}
}
//Driver program to test above function
int main()
{
// Let the given dictionary be following
char Dict[][20] = {"go", "bat", "me", "eat",
"goal", "boy", "run"} ;
// Root Node of Trie
TrieNode *root = getNode();
// insert all words of dictionary into trie
int n = sizeof(Dict)/sizeof(Dict[0]);
for (int i=0; i Java
// Java program to print all valid words that
// are possible using character of array
public class SearchDict_charArray {
// Alphabet size
static final int SIZE = 26;
// trie Node
static class TrieNode
{
TrieNode[] Child = new TrieNode[SIZE];
// isLeaf is true if the node represents
// end of a word
boolean leaf;
// Constructor
public TrieNode() {
leaf = false;
for (int i =0 ; i< SIZE ; i++)
Child[i] = null;
}
}
// If not present, inserts key into trie
// If the key is prefix of trie node, just
// marks leaf node
static void insert(TrieNode root, String Key)
{
int n = Key.length();
TrieNode pChild = root;
for (int i=0; iC#
// C# program to print all valid words that
// are possible using character of array
using System;
public class SearchDict_charArray
{
// Alphabet size
static readonly int SIZE = 26;
// trie Node
public class TrieNode
{
public TrieNode[] Child = new TrieNode[SIZE];
// isLeaf is true if the node represents
// end of a word
public Boolean leaf;
// Constructor
public TrieNode()
{
leaf = false;
for (int i =0 ; i< SIZE ; i++)
Child[i] = null;
}
}
// If not present, inserts key into trie
// If the key is prefix of trie node, just
// marks leaf node
static void insert(TrieNode root, String Key)
{
int n = Key.Length;
TrieNode pChild = root;
for (int i = 0; i < n; i++)
{
int index = Key[i] - 'a';
if (pChild.Child[index] == null)
pChild.Child[index] = new TrieNode();
pChild = pChild.Child[index];
}
// make last node as leaf node
pChild.leaf = true;
}
// A recursive function to print all possible valid
// words present in array
static void searchWord(TrieNode root, Boolean []Hash,
String str)
{
// if we found word in trie / dictionary
if (root.leaf == true)
Console.WriteLine(str);
// traverse all child's of current root
for (int K = 0; K < SIZE; K++)
{
if (Hash[K] == true && root.Child[K] != null )
{
// add current character
char c = (char) (K + 'a');
// Recursively search reaming character
// of word in trie
searchWord(root.Child[K], Hash, str + c);
}
}
}
// Prints all words present in dictionary.
static void PrintAllWords(char []Arr, TrieNode root,
int n)
{
// create a 'has' array that will store all
// present character in Arr[]
Boolean[] Hash = new Boolean[SIZE];
for (int i = 0 ; i < n; i++)
Hash[Arr[i] - 'a'] = true;
// tempary node
TrieNode pChild = root ;
// string to hold output words
String str = "";
// Traverse all matrix elements. There are only
// 26 character possible in char array
for (int i = 0 ; i < SIZE ; i++)
{
// we start searching for word in dictionary
// if we found a character which is child
// of Trie root
if (Hash[i] == true && pChild.Child[i] != null )
{
str = str+(char)(i + 'a');
searchWord(pChild.Child[i], Hash, str);
str = "";
}
}
}
// Driver code
public static void Main(String []args)
{
// Let the given dictionary be following
String []Dict = {"go", "bat", "me", "eat",
"goal", "boy", "run"} ;
// Root Node of Trie
TrieNode root = new TrieNode();
// insert all words of dictionary into trie
int n = Dict.Length;
for (int i = 0; i < n; i++)
insert(root, Dict[i]);
char []arr = {'e', 'o', 'b', 'a', 'm', 'g', 'l'} ;
int N = arr.Length;
PrintAllWords(arr, root, N);
}
}
/* This code is contributed by PrinciRaj1992 */输出：
go
goal
me